[Coco] CoCo repair-upgrade

Steven Hirsch snhirsch at gmail.com
Tue Sep 27 10:40:16 EDT 2011

On Tue, 27 Sep 2011, Mark McDougall wrote:

> On 27/09/2011 8:26 AM, Chad H wrote:
>> Actually, that's EXACTLY what I used...I tried desoldering braid
>> first...mixed results.  Tried vacuum desoldering bulb., only seems to
>> work if hit the part real quick before it cools.
> I use a $5 spring-loaded desoldering 'pump' myself. With a bit of practice, 
> just as good as any fancy-schmancy desoldering tool. The trick is to use 
> *enough* solder; some people seem to think that because you're trying to 
> remove the solder, starting with less is better. But the exact opposite is 
> true - generally you need to *add* solder before you start.

This is also true with dedicated vacuum desoldering stations.

> I'm about to attack an Acorn A3000 with a half-dozen 32-40 pin sockets that 
> need removing. Not looking forward to it, but just got an SMT rework station 
> so may try to put that to work on it...

I broke down earlier this year and purchased a Circuit Specialists 
"BlackJack" combo tool.  It comes with a temperature-controlled soldering 
iron, vacuum desoldering tool and hot-air reflow tool (the soldering iron 
and desoldering tool are mutually exclusive in terms of configuration).

Should have done this years ago...

A proper desoldering tool makes the difficult absolutely trivial once you 
get the temperature settings right.  At present, my hot-air reflow 
technique is a bit crude, but I was able to repair battery leak dameage 
on my Amiga A4000 (remove and replace a number of SMT 74LS parts along 
with trace repair).  Spending a lot of time practicing on dead PC 
motherboards :-)



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